Purge system

ABSTRACT

To measure flow rates, the cross-sectional shape of the flow path is changed by inserting a multiple position gate into the flow path and altering the position of the gate to maintain the head of liquid constant with a reduced flow cross section. The position of the multiple position gate is correlated with the depth as measured with a bubbler to provide an indication of flow rate. To purge the bubbler line, a purge tank is located near the bubbler line. At timed periods or as manually initiated the controller causes an increase in pressure in accumulator portion of the purge tank. When a predetermined pressure is reached, a purge valve in the purge tank opens, rapidly allowing a burst of air at a substantial pressure and velocity to flow through the bubbler line to remove any material adhering to the bubbler outlet port. For this purpose, the purge tank acts as an accumulator until the pressure in the tank against the effective area of the inner portion of a purge valve element overcomes the resisting force of a spring, at which time the valve element moves slightly, permitting air to flow over a larger area of the valve element. This increases the area receiving the accumulator air pressure to include an outer portion of the valve element and this increased effective pressure area of the valve increases the force rapidly to cause the valve to snap open.

RELATED CASES

This application is a continuation of application Ser. No. 08/491,642,filed Jun. 19, 1995, now abandoned, which is a divisional application ofU.S. application Ser. No. 08/132,562 filed Oct. 6, 1993, now U.S. Pat.No. 5,425,390, which is a divisional application of U.S. applicationSer. No. 07/937,493 filed Aug. 28, 1992, now U.S. Pat. No. 5,280,721filed by Timothy Carson and entitled PURGE SYSTEM, which is acontinuation-in-part of U.S. application Ser. No. 07/592,960 filed Oct.4, 1990, now U.S. Pat. No. 5,275,042 filed by Carson, et al., andentitled VARIABLE GATE FLOW ANALYZING METHOD AND APPARATUS.

BACKGROUND OF THE INVENTION

This invention relates to liquid depth measuring apparatus and methods,such as for example, are used in flow-rate measurements and in liquidsampling.

One class of flow meter performs depth measurements in a known flowpath. For such a measurement, a depth measuring instrument such as abubbler is used. The known flow paths may be controlled by a movablegate or obstruction in a flow stream that alters the flow to enableeasier measurement of flow rate.

In one type of prior art bubbler, clogging is reduced by purging theoutlet orifice of the bubbler from time to time with a faster flowingstream of air to clear the orifice. One such bubbler includes a purgesystem that accumulates air under pressure in a tank and opens the tankperiodically to cause a high pressure surge of air to clear the bubbler.

In a prior art purge system of this type, the purge system includes asolenoid operated valve to open the tank to the bubbler line. The tankshave been generally located near a controller and remote from thebubbler outlet port. It has from time to time been proposed to locatethe tank closer to the outlet port of the bubbler but this it not knownto have been implemented. The prior art arrangement in which a solenoidoperated valve opens an air tank near the controller has thedisadvantage of requiring a long air line between the solenoid operatedvalve and the bubbler outlet and the proposed system with a tank closeto the bubbler outlet would have had the disadvantage of requiring anelectric line to a location in or near the water. Long electric linesincrease the possibility of explosions from methane gas.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide a novel depthmeasuring instrument.

It is a further object of the invention to provide a novel bubbler.

It is a still further object of the invention to provide a noveltechnique for purging an underwater measuring instrument.

It is a still further object of the invention to provide a novel methodand apparatus for measuring flow rates of flowing fluids.

It is a still further object of the invention to provide a novel methodand apparatus for drawing samples from liquids to be analyzed.

It is a still further object of the invention to provide a novel methodand apparatus for altering the flow path of flowing liquids.

It is a still further object of the invention to provide a novelapparatus and method for calibrating flow meters and depth measuringdevices for liquids.

It is a still further object of the invention to provide a novel methodand apparatus for increasing the depth of moving liquids to permiteasier measurement of the liquids.

It is a still further object of the invention to provide a novel methodand apparatus for measuring characteristics of streams which method andapparatus are sufficiently versatile to make such measurements at eitherlow flow rates or high flow rates.

In accordance with the above and further objects of the invention, flowrates in a flow path are measured by changing the shape of the flow pathwith a barrier, determining the position of the barrier, determining acharacteristic of the flow path, and determining the flow rate. In thistechnique, the head of liquid pressure is measured with a bubbler andused with other measurements to determine the flow rate.

In one mode of operation, the barrier is maintained in a position suchthat the height of the fluid on the upstream side of the barrier remainsconstant at a height higher than in the unobstructed flow path, whereinthe measurement is made at a higher head of pressure and variations inbarrier position relate to flow rate. In another mode of operation, thebarrier is substantially removed from the flow path when the height ofthe fluid on the upstream side of the barrier reaches a predeterminedheight. Advantageously, liquid is sampled upstream from the barrier,whereby samples may be taken from fluid having a substantial depth.

For calibration of a bubbler used to measure upstream depth, a zeromeasurement is periodically obtained by opening a conduit to theatmosphere connected to the housing of the bubbler wherein the sensor isexposed to atmospheric pressure. The flow path for the bubbler isprotected by a shield and is kept clean by opening the gate to flushaccumulated solids downstream. The flushing may also be doneautomatically upon sensing excessive solids near the barrier such as bythe reflection of ultrasonic waves from the solids.

In the preferred embodiment, the bubbler may be purged by a separatepurge tank which builds up pressure and releases it at high pressureinto the bubbler outlet port to force the outlet port open by removingdebris. Periodically, in addition to the purging device, a larger bubbleis caused to be emitted to further maintain the port clear of debris.Calibration cycles are normally activated under control of a centralprogrammer.

The water flow-rate measuring and liquid sampling apparatus is morefully described in U.S. patent application Ser. No. 07/592960, filedOct. 4, 1990, now U.S. Pat. No. 5,275,042, in the name of Carson et al.This invention however differs from the apparatus in that disclosure inthat the depth measuring bubbler therein has been improved by theaddition of a purge apparatus designed to improve the reliability ofmeasurements and their precision in streams carrying potentialbubbler-outlet-port clogging materials. The disclosure of the aforesaidpatent application is incorporated herein by reference.

To purge the bubbler line, a purge tank is located in the near vicinityof the bubbler line and connected to a controller with electronics, avalve and a pump or reservoir that are located much further away. Attimed periods or as manually initiated, the controller starts the pumpor connects the pump to the tank and increases the pressure in the lineto the pressure of an accumulator portion of the purge tank. When apredetermined pressure is reached, a purge valve in the purge tank opensrapidly allowing a burst of air at a substantial pressure and velocityto flow through the bubbler line to remove any material adhering to thebubbler outlet port. The predetermined pressure is set by a biasingmember related to the head of pressure against which the air is to bereleased.

For this purpose, the purge tank acts as an accumulator until thepressure in the tank against the effective area of an inner portion of apurge valve element overcomes the resisting force of a spring, at whichtime the valve element moves slightly, permitting air to flow over alarger area of the valve element. This increases the area receiving theaccumulator air pressure to include an outer portion of the valveelement and this increased effective pressure area of the valveincreases the force rapidly to cause the valve to snap open.

Because the valve is able to automatically release fluid and accumulatefluid at periods of time related to the pressure setting of the biasingmember and the pumping rate of fluid into the accumulator, it has beenproposed that the valve may be used for other purposes such as tocontrol the cycling of a bladder pump of the type that repetitivelyinflates and deflates a bladder to change the volume of a pumpingchamber and thus pump fluid.

In making flow rate measurements using the bubbler, a flow housinghaving a tube with a flow path therethrough, an inlet and an exit ismounted to the flow path with a barrier for changing the depth of theflow path incorporated therein. Depth is measured with the bubblermounted in the housing upstream of the barrier. The barrier comprises agate mounted in said flow path, means for moving said gate such thatsaid gate can be positioned in any of open, closed and a plurality ofpositions between the open and closed position relative to said flowpath. By measuring the depth at different positions of the barrier andcorrelating this depth with the barrier position, the flow rate ismeasured.

From the above summary, it can be understood that the novel method andapparatus of this invention has several advantages, such as for example:(1) it is relatively simple, inexpensive and easy to use; (2) it permitsrelatively precise depth measurements, even in flow streams carryingmaterial capable of blocking a bubbler outlet port; (3) it is capable ofcooperating with a versatile apparatus that can be used both to measureflow rates and take samples in a wide variety of streams and at a widevariety of different depths of flow and flow rates; (4) it is capable ofgreat precision under difficult measuring conditions; (5) the apparatuscan be used to perform a number of different measuring methods; (6) thevalve can be used without electrical connection at the valve itself; and(7) it permits high-volumetric-rate air purging operations using asource near the bubbler outlet port without electrical connection.

SUMMARY OF THE DRAWINGS

The above-noted and other features of the invention will be betterunderstood from the following detailed description when considered inconnection with the accompanying drawings in which:

FIG. 1 is a block diagram of an embodiment of the invention;

FIG. 2 is a simplified broken away partly schematic drawing of a portionof the embodiment of FIG. 1;

FIG. 3 is an exploded, fragmentary, broken away, perspective view of aflow path, variable position gate and measuring apparatus in accordancewith the embodiment of FIG. 1;

FIG. 4 is an exploded perspective view of a portion of the embodiment ofFIGS. 1-3 from a viewpoint different from that of FIG. 3;

FIG. 5 is a block diagram of a portion of the embodiment of FIG. 1 forcontrolling the apparatus of FIGS. 2-4;

FIG. 6 is a front elevational view, party exploded and party broken awayof a purge tank used in the embodiments of FIGS. 1-5;

FIG. 7 is an elevational view of a portion of a bracket for the tank ofFIG. 7;

FIG. 8 shows a side developed view of the bracket of FIG. 6;

FIG. 9 shows the bracket of FIGS. 7 and 8 as an outwardly unfolded metalblank adapted to be bent into the bracket of FIGS. 7 and 8;

FIG. 10 is a side elevational view, partly exploded and partly brokenaway of the embodiment of tank of FIG. 6;

FIGS. 11, 12, 13 and 14 are a bottom view, front elevational view,sectional view through lines 13--13 of FIG. 11 and sectional viewthrough lines 14--14 of FIG. 11 respectively of a valve plate used inthe embodiments of FIGS. 6 and 10;

FIGS. 15 and 16 are a bottom view and sectional view through lines16--16 of FIG. 15 respectively of a valve element used in theembodiments of FIGS. 6 and 10;

FIG. 17 is a plan view of a diaphragm used in the embodiment of FIGS. 6and 10;

FIGS. 18 and 19 are a bottom view and sectional view through lines19--19 of FIG. 18, respectively, of a diaphragm retainer plate used inthe embodiment of FIGS. 6 and 10;

FIGS. 20 and 21 are a bottom view and sectional view through lines21--21 of FIG. 20, respectively, of an end plate used in the embodimentof FIGS. 6 and 10;

FIGS. 22 and 23 are an elevational view and sectional view through lines23--23 of FIG. 22, respectively, of a check valve housing used in theembodiment of FIGS. 6 and 10;

FIGS. 24 and 25 are an elevational view and sectional view through lines25--25 of FIG. 24, respectively, of a check valve used in theembodiments of FIGS. 6 and 10;

FIGS. 26 and 27 are an elevational view and a transverse sectional viewrespectively of the outlet assembly for the embodiment of purge tank ofFIGS. 6 and 10; and

FIG. 28 is a flow diagram of a program used in the embodiment of theinvention for purge operations.

DETAILED DESCRIPTION

In FIG. 1, there is shown one embodiment of a water flow rate measuringand liquid sampling apparatus 10 having a flow-stream local station 12,and a remote station 14 connected together with the flow-stream localstation 12 being partly within the flow stream and generally connectedtogether. It communicates with the remote station 14 through electricalconductors and pneumatic lines.

The flow-stream local station 12 and remote station 14 are arranged soas to alter the shape of a barrier to the flow stream and: (1) measurecharacteristics of the stream such as depth which permits a calculationof flow rate or other data; and (2) in some embodiments, draw samples offluid for later analysis.

The flow-stream local station 12 includes a gate position sensing system20, a flow cross section control system 22, a bubbler depth sensingsystem 24 and a liquid sampler inlet system 26. The flow cross sectioncontrol system 22 and the gate position sensing system 20 areinterconnected and communicate with the remote station 14 so that thegate position sensing system 20 indicates a gate position to the remotestation 14 which in turn sends signals to control the flow cross sectioncontrol system 22 and alters the barrier. In the preferred embodiment,the barrier is a gate-like structure that provides a greater or lowercross sectional area of flow projected into the direction of the flowingstream.

The bubbler depth sensing system 24 and the flow cross-section controlsystem 22 also communicate with the remote station 14 to: (1) send backsignals indicating depth, such as by indicating the head of pressure ata location in the bottom of the flow path; and (2) draw samples from anappropriate location for pumping to the remote station. The signals areinterpreted in the light of the position of the barrier and the barriercan aid in creating a still location for appropriate samples to bedrawn.

The remote station 14 includes a gate positioning and bubbler controlsystem 30, a flow rate analyzer 32, a depth analyzer 34, a display andprinter section 36, a sampler system 38 and a central control system 40.The depth analyzer 34 is electrically connected to the flow rateanalyzer 32 and the gate positioning control system 30 to providesignals thereto indicating the depth of the flow stream.

The flow rate analyzer 32 receives signals from the gate positionsensing system 20 and from the depth analyzer 34 and transmits signalsto the central control system 40. The central control system 40, inresponse, transmits signals to the gate positioning control system 30 tocontrol air and/or electrical signals controlling the gate and bubbler.The gate position sensing system 20 transmits information to the flowrate analyzer 32 and the flow rate analyzer 32 utilizes this informationtogether with the information received from the depth anaylzer 34 tocalculate flow rate. The sampler system 38 communicates with the liquidsampler inlet system 26 to periodically draw samples at times that areappropriate for later analysis.

The central control system 40 receives signals from the depth analyzer34, the gate positioning control system 30, the flow rate analyzer 32,the display and printer section 36 and the sampler system 38. Itutilizes those signals to control each of the above units and preparedata for display and printing by the display and printer section 36.Thus, the central control system 40 can make necessary calculations andstore information such as look up tables related to coordination ofdepth and flow rate or can calculate values utilizing the Manningequations and display and print data as desired. It can also time andrecord the time of the drawing of samples by the sampler system 38.

In FIG. 2, there is shown a broken away elevational view sectioned toshow the flow-stream local station 12 mounted within a flow stream 42and including the liquid sampler inlet system shown generally at 26, thedepth sensing system shown generally at 24 within the flow stream 42.The flow cross section control system 22 is mounted in place in closecooperation with the gate position sensing system 20. A clamping unit 44positions the flow path bed and the housing for level flow as explainedhereinafter.

The flow stream 42 may be any flow bed for a liquid together with theliquid itself. In FIG. 2, there is shown as part of the flow stream 42,a pipe 46 with a bed of water 48 which may contain debris or sewage orthe like such as would be carried by sewage lines in a city. In FIG. 2,the pipe 46 extends into a manhole indicated by the walls of 49generally so that the flow cross section control system 22 extendspartly into the pipe 46 and partly beyond it into the manhole.

The bed of water 48 for convenience is considered as having an upstreamportion 50 which enters the flow cross section control system 22 and adownstream portion 52 which exits it beyond a barrier to be describedhereinafter. The dividing line between the upstream portion 50 anddownstream portion 52 of the flowbed is the barrier controlled by theflow cross section control system 22.

The flow cross section control system 22 includes a flow housing 60, agate assembly 62 and a gate control assembly 64. The gate assembly 62and gate control assembly 64 are mounted together so that the gatecontrol assembly 64 controls the gate assembly 62 in forming a barrierto the upstream portion 50, which barrier changes its shape insofar asit projects a different profile upstream of the flow. The gate assembly62 and gate control assembly 64 are mounted to the flow housing 60 bythe clamping unit 44, which in turn, is mounted to the flow stream 42 toreceive the flow of liquid 48.

To mount the flow housing 60 in position where it receives the flow ofliquid 48 at the gate assembly 62 and gate control assembly 64 properly,the flow housing 60 includes a sealing section 70, a flowbed section 72,a gate housing section 74 and the clamping section 44. The gate controlhousing 74 includes within it the mechanism for positioning the gateassembly 64 and the gate position sensing system 20. The flowbed section72 includes internal walls 76 which receive the water 48 or watercombined with sewage or debris or the like from upstream and supportsits flow downstream. It is sealed by the sealing section 70 to the flowbed or flow stream 42 so that all of the water or other liquid to bemeasured flows into the flowbed section 72. The gate housing section 74is joined to the flowbed section 72 and clamping section 44 clamps theentire assembly in position to the flow stream 42.

In the preferred embodiment, the flow stream 42 is a cylindrical pipeand the internal walls 76 of the flowbed section 72 is a conforminglyshaped cylinder slightly lower in outer diameter than the inner diameterof the walls of the pipe 46, forming a portion of the flow stream 42.However, the flow stream 42 may assume other shapes and the internalwalls 76 will also take other shapes in such a case.

To mount the gate assembly 62, the gate control assembly 64 and gateposition sensing system 20, the gate housing section 74 of the flowhousing 60 includes internal walls which are rigidly mounted to orintegrally formed with the internal walls 76 of the flowbed section 72that extend upwardly so as to be usually, or in most installationsabove, the upstream portion 50. To this gate housing section 74 aremounted the gate position sensing system 20, the gate control assembly64 and the gate assembly 62 which extends downwardly into the liquid 48to divide the upstream portion 50 from the downstream portion 52. InFIG. 2, the gate housing section 74 is fragmentary and shown broken atits uppermost portion.

To seal the internal walls 76 against the walls of the pipe 46, thesealing section 70, in the preferred embodiment, includes a bladder 80,a pneumatic bladder tube 82 and retaining members 84A and 84B in oneembodiment for sealing the bladder 80 to the internal walls 76. Withthis configuration, after the flow cross section control system 22 andgate position sensing system 20 are in place within the pipe 46, air maybe applied to the bladder 80 through the pneumatic bladder tube 82 toinflate it and form a sealing connection between the internal walls 76and the walls of the pipe 46.

To form a barrier to the flow of the liquid 48, the gate assembly 62includes a plastic plate portion 90 and a plurality of integrally formedridges extending from its surface, such as 92 and 94 in the preferredembodiment. One of those ridges centrally located cooperates with thegate control assembly 64 that pivots the gate upwardly away from theliquid stream 48 or downwardly into its surface and at greater depths tocreate a barrier in the liquid which will cause the upstream portion 50to be higher than the downstream portion 52.

The plastic plate portion 90 includes two yokes, 96A unit and 96B, (96Aonly being shown in FIG. 2) cut into its end and pivotably mounted toone wall 77 of the gate control housing. The gate control assembly 64includes a yoke 100, a piston shaft 102, an ear 104, a piston diaphragm106, a helical compression spring 108, a pneumatic tube 110 and a piston105 (not shown in FIG. 2). The piston shaft 102 is connected to thepiston 105 under the diaphragm 106 at one end and at the other end hasthe yoke 100. The ear 104 is integrally formed with or fastened to theinternal wall 77 of the gate housing 74 spaced from the movable pistonshaft 102 and cooperates with a yoke 96A by receiving a pin 112. Asimilar ear cooperates with a yoke 76B (FIG. 4).

The yoke 100 similarly receives a pin and is pivotably mounted to theridge 92 so that as it moves up and down, it causes movement of theplastic plate portion 90 with respect to the ear 104, which pivots aboutthe pin 112 through the yoke 96. The helical compression spring 108 ismounted between the piston 106 and a wall 114 of a piston chamber withinwhich the piston bladder 106 moves. Below the piston bladder spring 108helical compression spring 108 communicates with the cylinder so thatair pressure applied by the tube 110 to the upper part of the pistonchamber moves the piston and piston bladder 106 downwardly against theforce of the compression spring 108. When the pressure is released, thespring 108 moves the piston 106 upwardly to move the shaft 102 upwardly,which in turn pivots the gate assembly 62 about the pin 112 upwardly andaway from the bottom of the liquid 48. Similarly, pressure applied tothe chamber wall 114 above the piston diaghram 106 through the tube 110(see FIGS. 3 and 11 for location) moves the gate assembly 62 downwardlyinto increasing depths of the liquid 48, where it may be held bymaintaining the gas pressure in the chamber.

The gate position sensing system 20 includes a shaft 120 and a positionsensor 122. The shaft 120 is connected at one side to the piston 105(under bladder 106) and at its other side to a core of the sensor 122 sothat as the piston 105 moves upwardly and downwardly, the shaft 120moves and causes the sensor 122 to generate a signal indicating theposition of the piston 105 and therefore the gate assembly 62.

The position sensor 122, in the preferred embodiment, is a LVDT (linearvariable-differential transformer) which generates a signal that varieslinearly with shaft 120 movement. It is energized by two of theconductors 124 and applies a signal on two other conductors, all ofwhich are in the cable 124.

The liquid sampler inlet system 26 includes a conduit which communicatesin a typical manner through a fitting or the like, preferably in thegate assembly 62, for drawing under the control of a sampler system 38(FIG. 1) periodic samples of fluid for analysis. It is generally locatedon the gate assembly 62 at a location which has sufficient depths, issufficiently nonturbulent to draw representative samples andsufficiently turbulent to reduce clogging. Prior to drawing a sample,the gate assembly 62 may be opened so as to remove solids and thenclosed until the depth is sufficient for taking a sample.

To determine the depth of the fluid, a bubbler tube 132 is mountedadjacent to the bottom wall 76 of the flow path and under a protectivecover and flat calibrating surface 130. The pressure measuring point orentrance to the housing of the bubble tube is at location 134approximately 0 inches from the location of the gate to 2 feet whenfully closed. It should be at a known elevation from the end of the gateassembly or the same elevation. The location is selected to besufficiently far from the end of the wall 76 and of the gate so thatneither the gate nor the flow of water from the end of the wall 76 intoa manhole affect the measurement by velocity effects such as Venturieffects or by having an unusual rise or lowering of the liquid level atthat point but sufficiently close to obtain scrubbing from the velocityof the liquid flowing over it.

To mount the flow cross section control system 22 to the flow stream 42(pipe 46), an adjustable clamping unit 44 includes a bracket 140, afirst adjustable clamp 142 and a second adjustable clamp 144. The firstand second adjustable clamps 142-144 each include an adjustable platewith a curved clamp portion mounted thereto to grip the walls of thepipe 46, one curved clamp member being shown at 146 formed integrallywith the outer plate of the second or outer adjustable clamp 144. Theclamping plates 142 and 144 are pivotable about the bracket 140 andadjustable with respect to each other so that the flow cross sectioncontrol system 22 may be positioned at different heights and angles withrespect to the clamping means.

In FIG. 3, there is shown an exploded perspective view partly brokenaway of the flow cross section control system 22, gate position sensingsystem 20 and depth sensing system 24 mounted together and showing onlythe bracket 140 of the clamping means.

As best shown in this view, the gate assembly 62 includes threereinforcing ribs 93, 92 and 94 with the rib 92 fitting within the yoke100 of the shaft 102 and being pinned therein by a pin 150 for pivotablemovement about the pins 112A and 112B (112B not shown in FIG. 3) throughthe ear 104A and 104B (ear 104B not shown in FIG. 3) and the yokesformed of the cutout portion 96A and 96B (96A only shown in FIG. 3) ofthe gate assembly 62 so that as the shaft 102 moves upwardly anddownwardly, the gate is raised and lowered as the LVDT senses itsposition and transmits it through a cable 124 to the remote station 14(FIG. 1).

A gate insert or opening 152 extends through the rib 92 and a plate 90to face upstream, thus serving as a sample inlet 26. The samples aredrawn to the surface through a tube 252. Sampling at this locationprovides representative samples. They are drawn within 15 minutes afterclosing the gate and as soon as the liquid is sufficiently high such as3 or 4 minutes.

A bubble level 156 is mounted on top of the housing 74 and may be usedin conjunction with the adjustable clamping unit 44 (FIG. 4) to causethe wall 76 to be horizontal for accurate measurement by an operatorlooking down so as to be free from the flow into the manhole.

The bracket 140 is generally shaped in cross section as a U facing onits side so as to provide a front surface and side wings which may befastened by bolts to the wall 76, such as by the bolts 150A and 150B orby any other convenient fasteners and thus support a pivot point andlocking screws (not shown in FIGS. 2 and 3) as well as the adjustableclamps 142 and 144 (FIG. 2).

As best shown in this view, a purge tank 350 is mounted to the walls ofthe gate housing section 74 and connected by a purge air line 382 to oneleg of a tee connection 390. The other legs of the tee connection areconnected in line with the bubbler tube 132 so that the line 382communicates with the line 132 to provide an added flow of purge airtherethrough during a purge cycle but is otherwise closed and out of theconnection with the bubbler 132. With this arrangement, the purgeassembly is connected near the bubbler outlet port and within three feetthereof, being connected on the port side of the restrictor 318 so as tobe capable of providing an unrestricted high velocity flow of air to thebubbler outlet port for purging thereof.

It is also possible to connect the lines internally to the housing ofthe purge system instead of using a tee connection external. Theexternal tee connection is used for clearity in FIG. 3.

In FIG. 4, there is shown another exploded perspective view of the gateposition sensing system 20, the gate control assembly 64, and the gateassembly 62 as they are mounted together. As shown in this figure, thegate housing 74 includes a plurality of disassemblable sections 74A,74B, and 74C to permit ready access to the gate assembly 62, gateposition sensing system 20 and gate control assembly 64.

To support the gate assembly 62, the gate position sensing system 20,and the gate control assembly 64, the gate assembly 62 is mounted to thehousing 74 by yokes 96A and 96B and the gate position sensing system 20is mounted to the gate control assembly 64 by brackets 160 and 162 andto the housing 74 by bracket 164. The brackets and portions of thehousing are held together by conventional screws, bolts, nuts and pinssuch as those shown at 166A-166F.

To seal a conductor 124 when not electrically connected and to provide asocket for connecting electrical wires, a connector 180 fits within thehousing member 74B so that it may be sealed when not connected to acable by cap 182. Similarly, the pneumatic conduit 110 for energizingthe piston and thus the shaft 102 communicates with a connector 184 forconnection to an external pneumatic tube. In the preferred embodiment,one connector is used for both pneumatic and electrical connectors.

As shown in this view, the purge tank 350 is mounted to the housing 74by the bracket 388 to be readily attached to existing flow controlsystems and the bubblers used in them. It is connected to a portion of ameasuring and sampling system near the port of a bubbler for easyconnection on the port side of the restrictor. Of course, it could beused with other bubblers or other systems that need a burst of fluidsuch as to clear them. system

In FIG. 5, there is shown a block diagram of another embodiment ofremote station 14A similar to the embodiment 14 of FIG. 1 having anelectronic portion 270 and an air portion 272. The embodiment 14Aperforms the same functions as the embodiment 14 of FIG. 1 but utilizesa standard microprocessor and a standard LVDT. The program used in thepurge operation is attached hereto as Attachment A and a flow diagram inaccordance therewith comprises FIGS. 28 to be described hereinafter.

The electronic portion 270 includes as its principal parts, amicroprocessor 280, an input output section 282, certain interfaces 284,an analog to digital conversion section 286 and a LVDT control section288. All of these sections communicate with the microprocessor 280through a central bus 289 so that the microprocessor 280 can; (1)provide signals to the interface section 284; and (2) receiveprogramming and data from and provide signals to the input-outputcircuits 282. Similarly, the analog to digital conversion section 286serves as an interface for the microprocessor 280 and other units, beingconnected to the air portion 272 to receive analog pressure signalsrepresenting depth and to the LVDT control system 288 to receivebuffered analog signals indicating gate position.

To provide as a centralized source of calculations and controloperations, the microprocessor 280 includes a CPU (central processingunit) 290, a program memory 292 and a data memory 294. These unitsfunction together to make calculations and perform control operations.The program memory 292 includes inter alia a look-up table capable ofproviding flow rates in response to depth information and gate positioninformation under the control of the central processing unit 290. Theinput-output circuits 282 receive information from a keypad 296, supplysignals to certain drivers 298 for driving a plotter 304 in a mannerknown in the art, and receive and transmit signals from and to themicroprocessor 280.

The interfaces 284 include buffering interfaces to provide signalsreceived by it from the computer unit 280 to the sampler, the remoteplotter and any other units with which it may be desirable tocommunicate but which require buffering different than that provided bythe input-output circuits 282.

The analog to digital conversion section 286 includes two analog todigital converters 300 and 302, one of which is connected to receiveanalog signals from the LVDT control 288 which receives analog signalsfrom the gate position sensing system 20 and buffers them forapplication to the analog to digital converter 302 and the other ofwhich receives signals from the air portion 272 indicating pressure uponthe depth sensing system 24 (FIG. 1). These units communicate with adisplay 306 to display data, with the computer system 280 forcalculations and with the input-output circuits 282 for operating thedriver 298 and plotter 304.

The central processing unit 290, in the preferred embodiment, is aHitachi America, Ltd, Number HD6418ORCP-6X available from the HitachiAmerica Ltd., Semi-Conductor and IC Division, 2210 O'Toole Avenue, SanJose, Calif. 95131. This is an 8-bit microprocessor referred to as aHD64180 8-bit Microprocessor.

The air portion 272 includes an air pump 310, an air reservoir 312, gatecontrol valve 314, bubbler control valve 316, an air restrictor 318, avalve 317, a purge valve 396, a purge assembly 350, a pump 402 and apressure sensor 320. The air pump 310 supplies air under pressure toreservoir 312 through a conduit 322 in response to signals received overan electrical conductor 324 from the input-output circuits 282. Pressureis supplied by the reservoir 312: (1) directly to the control valves 314for the gate positioning control system 30 for positioning the gateassembly 62; and (2) through a restrictor 318 for operating a bubblerthat includes a port 24 (FIGS. 1, 2 and 4). Valve 316 connects thepressure sensor 320 to atmosphere through conduit 329 for calibration orin another position to the bubbler port and restrictor to sensepressure.

To maintain the bubbler port clear, valve 317 when opened connects thereservoir to the bubbler port for a speed up super bubble. This valvemay also be used for purging by holding it open for a longer time. Thepurge assembly 350 is connected by a purge air line 382 and a tee 390 tothe bubbler tube 132. In the preferred embodiment, its air inlet iselectrically connected to the reservoir 312 and a sensing outlet iselectrically connected to the pressure sensor 320 or may be connected toa separate sensor 394. In either case, the electrical signal isconverted to a digital signal and the program in the control sectionutilizes this signal to control the operation of the purge system.However, its air inlet may instead be connected through the solenoidcontrol valve 396 which in turn communicates with the reservoir 312 orwith a pump 402. If it communicates with the valve 396, the valve iselectrically connected to the conductor 325 to receive a signalinitiating a purge or in the alternative, the pump 402 is electricallyconnected to conductor 325 to be started and stopped.

To position the gate assembly 62, the gate assembly is moved and held:(1) down by applying pressurized air from the reservoir 312 to thecompartment above piston 106 (FIG. 2) through a first conduit 326 bypulsing one of the valves 314 with a signal on conductor 324; and (2)upward by venting air to atmosphere through the other valve 314 to aconduit 328, in which case, the spring 108 (FIG. 2) moves the gateassembly 62 (FIG. 2) upwardly to the new position established bypressure in the reservoir above the piston 106. This motion causes theLVDT to provide a new signal to the control unit 288 as feedback forcontrolling the position of the gate assembly 62.

To calibrate the pressure sensor 320 and/or the pressure sensor 394, thevalve 316 is mounted near the pressure sensor 320. To free the systemfrom losses that vary with tube length, the restrictor is connected nearthe bubbler port 24 in the housing of the gate assembly. The valve 316:(1) is activated to vent the tube 252 to atmosphere through a conduit329 in one position for calibration; and (2) to connect line 252 fromthe outlet of the restrictor 318 and outlet port 24 to conduit 251 toapply pressure representative to sensor 320 which in turn supplies anelectrical signal on conductor 330 to the analog to digital converter300.

The restrictor 318 in the preferred embodiment is mounted in the housingof the local station so that it is near the bubbler outlet port 24 andthe pressure applied to the pressure sensor 320 is not affected by thelength of bubbler tube extending to a location near or in the remotestation. This tube may be long and may thus introduce pressure errorsfrom resistance even if the bubbler tube is between the pressurecontrolling restrictor and the port 24 if it is long.

While in the preferred embodiment, the restrictor is mounted in thehousing, it could be mounted at some other location, preferably near theport 24 if this is convenient. For example, it could be mounted within10 or 15 feet of the port. By mounting this restrictor close to theport, a smaller diameter air tube can be used for the bubbler and thispermits the air tube to fit within a small connector along with the airtube for controlling the gate control mechanism and the electricalconductors because the pressure drop in the tube can be compensated.

In FIG. 6, there is shown a partly-broken-away, partly-explodedelevational view of the bubbler purge system 350 having a bubbler purgesystem housing 386, a bracket 388, an accumulator assembly 356, a purgevalve assembly 352 and an outlet assembly 378. Air from the reservoir312 (FIG. 5) flows through line 398 (FIG. 5) and either directly intothe accumulator assembly 356 or through the valve 396 (FIG. 5) into theaccumulator assembly 356. This assembly is within the housing 386 and iscooperatively mounted to the purge valve assembly 352 and the outletassembly 378 so that when the pressure in the accumulator assemblyreaches a predetermined value, the valve assembly 352 opens a pathwayinto the outlet assembly 378 to purge the bubbler 132 (FIG. 5). Insteadof receiving air from the reservoir 312, the accumulator assembly 356may receive air directly from a pump 402 as described in connection withFIG. 5.

The bracket 388 is mounted to the bubbler gate housing 74 and for thispurpose includes eyelets 408A and 408C to receive bolts or fastenerstherefore. It surrounds and grips the purge assembly housing 386 and isfurther fastened by machine screws 406A and 406B (only 406A being shownin FIG. 6) which fit within the slots 404A and 404B respectively (only404A being shown in FIG. 6).

To accumulate air under pressure, the accumulator assembly 356 includesan inlet port 410, a valve seat 358, a valve seat plate 354, and acompartment 422 occupying most of the interior of the housing 386.Tapped holes 412A and 412B in the valve seat plate 354 are used tofasten the valve assembly to the housing 386 in a manner to be describedhereinafter. With this arrangement, the accumulator assembly 356 ismounted to the purge valve assembly 352 and the outlet assembly 378 tocooperate in accumulating air under pressure and suddenly releasing itfor purging operations in a fast flow with a snap action.

To control the accumulation of air and its release, the purge valveassembly 352 includes a purge valve element 362, a retainer plate 366, aretainer nut 368, a spring 370, a bottom plate 372 and a rollingdiaphragm 364. The bottom plate 372 is mounted to the housing 386 by thescrews 374A and 374B which pass through the bottom plate and washers376A and 376B, being threaded into the tapped holes 412A and 412B in thevalve seat plate 354 to hold the purge valve element 362, retainer plate366, retainer nut 368 and rolling diaphragm 364 in place to operatecooperatively with the valve seat plate 354 within the accumulatorassembly 356. The rolling diaphragm is a member that when depressedunrolls loose material rather than only stretching and thus can be movedfurther.

With this arrangement, as air pressure builds within the chamber 422,pressure moves the purge valve element 362 downwardly, causing the airto exert further force on the rolling diaphragm 364 to increase theforce rapidly. This increased force causes the valve to open fully topermit the rapid escape of air through the outlet assembly 378 byrapidly forcing the spring 370 downwardly to unblock the outlet assembly378.

The outlet assembly 378 includes a purge air line or tubing 382, a portassembly 380, and an air pressure sensing outlet 384. The outlet 384communicates with a line to be described hereinafter to supply airpressure to a pressure sensor that generates signals for the centralcontroller. The air line or tubing 382 communicates with the portassembly 380 and with the bubbler line 132 (FIGS. 3 and 5) to supply airunder pressure rapidly during a purge operation.

In FIGS. 7, 8 and 9, there are shown an elevational view, a top view anda developed view of the bracket 388 respectively. As shown best in FIG.7, the bracket 388 includes a top portion 414 and a bottom portion 416.The top portion includes slots such as 404A to receive a correspondingmachine screw such as 406A (FIG. 6). The three openings 408A-408C extendvertically through both the top portion 414 and the bottom portion 416,serving to hold the bracket around the housing 386 (FIG. 6) for mountingpurposes and to provide a means for fastening to the gate housing 74(FIG. 3).

As best shown in FIG. 8 and 9, the bracket is formed by stamping anelongated plate from stainless steel, resulting in an integrally formedmember with the slots 404A and 404B positioned to be on opposite sidesof the housing 386, openings 408A-408C extending downwardly on one edgeof the portion 416 and the openings 418A and 418B aligning with theopenings 408A and 408B on the opposite edge of the portion 414 so thatwhen bent as shown in FIG. 8, the openings 408A and 408B are alignedrespectively with the openings 418A and 418B and a loop is formed to fitaround the housing 386 (FIG. 6).

In FIG. 10, there is shown an elevational view, partly-broken-away,partly exploded and partly sectioned of the bubbler purge system 350with the broken away and sectioned portion having a valve seat outletrotated 90 degrees about a vertical axis so that it shows in thesectioned portion. This purge system has an accumulator assembly 356, apurge valve assembly 352, and the outlet assembly 378 exploded to agreater degree than that shown in FIG. 6 and being a right elevationalview rather than a front elevational view as is the case with FIG. 6.

As shown in FIG. 10, the accumulator assembly 356 includes the valveseat plate 354, the inlet 410, and the compartment 422. These partscooperate as explained in connection with FIG. 6 so that, when the airpressure builds in the compartment 422 to a predetermined level, thepurge valve assembly snaps open and releases air through the outletassembly for a purging operation.

For this purpose, the valve seat plate 354 includes a valve seat 358, avalve guide 426, the air holes 430A and 430B, an annular valve chamber436, and a valve seat outlet port 454. These parts are positioned sothat the valve seat receives the purge valve assembly 352 in oneposition to seal the outlet assembly and in another position to open theoutlet assembly.

For the purpose of this cooperation, the purge valve assembly 352includes an O-ring 424, the purge valve element 362, the rollingdiaphragm 364, the retainer plate 366, the retainer nut 368, the spring370 and the bottom plate 372. These units are mounted to the housing bythe machine screws 374A and 374B and the corresponding washers 376A and376B which pass through openings in the end plate and into holes such asshown at 412A and 412B (FIG. 6) in the valve seat plate 354.

The O-ring 424 is compressed between a portion of the valve seat 358 anda top surface of the purge valve element 362, forming a seal against theflow of air from the accumulator compartment 422 through valve seatoutlet port 454 to the outlet assembly 378. This outlet communicateswith the annular chamber 436 to receive air therefrom and permits theflow of air through the outlet assembly 378 when the O-ring 424 isreleased by the depression of the spring 370.

The downwardly extending cylindrical valve guide 426 fits through anopening 428 in the purge valve element 362, which opening extendsdownwardly to a closed end. With this arrangement, the valve element 362is kept aligned as it moves upwardly and downwardly under the control ofthe air pressure within the compartment 422 and of the force of thespring 370.

To close and open the valve seat outlet port 454, the purge valveelement 362 includes an inner portion 432 inside the O-ring 424 and anouter portion 434 outside the O-ring within the rim of the purge valveelement 362 and recessed in its flat inner surface. It includes steppedcylindrical bosses, one of which is externally threaded, and both ofwhich fit within an opening in the retainer plate 366 to be held theretoby the nut 368. The the rolling diaphragm 364 is held between the valveelement 362 and the retainer plate and extends beyond them to engage thetop annular end of upwardly extending walls on the bottom plate 372. Thenut 368 is threaded on the shoulder to hold the rolling diaphragm 364 inplace, with the helical spring 370 fitting around the shoulder of theelement 362 and abutting the bottom plate 372.

The outlet assembly 378 includes the port assembly 380, the purge airline 382 and the air pressure sensing outlet 384, with the air sensingoutlet 384 extending through the outlet housing for connection to asensing line 392 (FIG. 5). The port assembly 554 includes an outer spoutconnection 385 for engaging the purge air line 382 that eventuallyconnects to the bubbler 132 (FIGS. 1-5) through tee connector 390 (FIGS.3 and 5).

The port assembly 380 includes the check valve housing 440, an O-ring442, a check valve 444 and a tank outlet housing 446. With thisarrangement, the check valve 444 includes a small opening 544 (FIG. 25)for the bleeding of air. This is intended to maintain the pressure atthe pressure of the bubbler line or atmospheric pressure to establish astandard pressure for the setting of the spring. The check valve is setat a low force to prevent premature loss of pressure before the valveopens. It receives air from the compartment 422 through its inlet port524 and when open permits it to escape through openings 546A-546Cbetween inner wall members 532 into the outlet housing 446 and fromthere to the purge air line 382 and the sensing connection 384.

FIGS. 11-14 are a bottom view, front elevational view, and twodiametrecal transverse sections respectively of the generallycylindrical valve seat plate 354 having, as best shown in FIG. 11, anannular recess 458, a cylindrical downwardly extending valve guide 426,holes 430A and 430B, a downwardly extending annular sealing cylindricalwall 456of the valve seat 358, an annular recessed valve chamber 436, adownwardly extending cylindrical rim 460 and a valve seat outlet 454.The valve guide 426 is cylindrical and extends downwardly from thecenter of the valve seat within the central recess 458 which has acircular cross-section.

The two holes 430A and 430B are on either side of the guide 426 and asbest shown in FIG. 13, extend all the way through the plate adjacent tothe post 426 within the recess 458 to permit the passage of air from thecompartment 422 (FIG. 10) into the space formed by the recess 458 toexert downward pressure on the inner area surrounding the guidepost 426on the purge valve assembly 352.

The recess 436 is sealed from the holes 430A and 430B and thecompartment 422 by the engagement of the O-ring 424 (FIG. 10) with thedownwardly extending wall or annular sealing ring 456 of the valve seat358 when the purge valve assembly 352 is closed and exerts a pressureequal to the pressure in the compartment 422. Thus, the pressure resultsin exerts a force against the spring 370 (FIG. 10) equal to the area ofthe valve element 362 that seals the recess 458. This area is referredto from time to time as the purge valve inner area.

As best shown in the sectional views of FIGS. 13 and 14, the openings430A and 430B (FIG. 13) connect the compartment 422 to the inner areadefined by the inside of the O-ring 424 (FIG. 10) but provide theannular recess 458 which fills with air from the compartment 422 (FIG.10) at the same pressure as the compartment 422 and exerts pressureagainst the valve, tending to open the valve. The inner area issufficiently large so that at the design pressure provided by thereservoir, the valve opens slightly to break the seal between the O-ringand the annular sealing ring 456 of the valve seat 358 so that air flowstherebetween.

As soon as air starts flowing beyond the annular ring 456 of the valveseat 358 into the recess 436 forming the annular valve chamber, thetotal force against the spring 370 is rapidly increased because the areareceiving the same pressure as the compartment 422 increases. Since thispressure is the same as in the compartment 422 and the area is muchlarge, the spring 470 is quickly overwhelmed and the valve snaps open.

As best shown in the elevational view of FIG. 12, the valve seat outletport 454 opens into the annular valve chamber to release air to theoutlet in a fast flow from the compartment 422. This onrush of air iswith high volume because the valve is now fully opened so that the valveserves as a snap-open switch, which when a threshold pressure isreached, moves quickly to a full open condition under the control ofonly hydraulic and mechanical forces. The opening is related to a ratioof two hydraulic forces moved by substantially the same hydraulicpressure which overcomes a biasing means (the spring 470).

In FIGS. 15 and 16, there is shown a bottom and transverse sectionalview, respectively, of the purge valve element 362 having a downwardlyextending spring engaging boss 462 in its center with an upwardlyopening guide hole 428 through it, a spring-receiving annular groove464, a cylindrical externally threaded portion 466, an upwardly openingO-ring groove 468 and a plate-receiving annular recess 500. The valveelement is adapted to move within a limited range of motion under thecontrol of a small space between the end cap 372 (FIG. 10) and the valveseat plate 354 under the control of air pressure from the compartment422 (FIG. 10) and the spring 370 (FIG. 10).

The movement of the valve element 362 is sufficient to compress theO-ring 424 against the annular sealing ring 456 in the valve seat 358 ofthe valve seat plate 354 to prevent air from passing O-ring 424 andthrough the outlet port 454 (FIG. 12) in one position or to move down toanother position a sufficient distance to snap open and permit highvelocity air to go through the outlet port 454 into the outlet assembly380 (FIG. 10) for a purging operation.

To provide the closing and opening operation for air utilized in thepurging operation, the spring engaging boss 462 fits within the spring370 (FIG. 10) and the top portion of the spring 370 is received by thespring-receiving annular groove 464 to be held therein and exert upwardforce against the force of air in the compartment 422 (FIG. 10). Therange of motion is controlled by the distance between the springreceiving boss 462 and the end cap 372.

As the valve element moves, the O-ring which normally resides in theO-ring groove 468 is loosened or tightened against the valve seat 358 toeither permit the escape of air or prevent the escape of air from thecompartment 422, with the plate receiving annular recess 500 receivingor moving from the downwardly extending portions of the valve seat plate354.

In FIG. 17, there is shown a plan view of the diaphragm 364 having acircular member 502, a centrally located opening 504, and side openings506A and 506B. The side openings 506A and 506B are adapted in size topermit the bolts 374A and 374B to pass therethrough into the valve seatplate 354 (FIG. 6) without preventing the inner portions of thediaphragm 502 to move a short distance. The centrally located opening504 fits around the cylindrical threaded portion 466 of the purge valveelement 362 so that the diaphragm cooperates with and is held to thevalve element 362 by the retainer plate 366 and nut 368 to form a largerdiameter impediment to air flow, that diameter extending throughout theinner diameter of the housing 386 to increase the area for air passingthrough the openings 430A and 430B (FIG. 10).

In FIGS. 18 and 19, there are shown a plan view and a side view of theretainer plate 366 having a circular diameter conforming to the diameterof the valve element 362, a central opening 363 which fits over thethreaded portion 466 of the purge valve element 362 (FIGS. 15 and 16)and a downwardly extending flange 365 forming a cylindrical recess thatreceives the nut 368 for threading against the threaded portion 466 ofthe purge valve element 362, so that when threaded onto the element 363,the diaphragm 364 is held in place for movement with the valve element362 and is capable of embarking force to the valve element caused by airescaping the compartment 422. Although a diaphragm has been described inthe preferred embodiment to prevent the escape of air, any othersuitable movable seal may be used such as a piston of or bellows or thelike in a manner known in the art.

In FIGS. 20 and 21, there is shown a plan view and a top view takenthrough section 21--21 of FIG. 20, respectively, having a circularbottom plate with an annular end flange 508, a central air hole 450,holes 438A and 438B for receiving the bolts 374A and 374B (FIGS. 6 and10) for holding the bottom plate to the housing and upwardly extendingannular wall portions 510, so that the bolts 374A and 374B hold thebottom plate 372 with the annular wall portions 510 abutting against thedownwardly extending cylindrical rim 460 (FIG. 13) and holding thecircular member 502 (FIG. 17) of diaphragm 364 between them.

With this arrangement, the upwardly extending walls enclose the purgevalve element 362, the O-ring 424, the diaphragm 364, the retainer plate368, the retainer plate 366, the retainer plate nut 368 and the spring370. The valve element 362 is permitted to move slightly within thebottom plate 372 to open a path for air through the outlet 378 and closethat path in such a way to provide sudden bursts of purging air to thebubbler 132.

In FIGS. 22 and 23, there is a shown an elevational view and atransverse section view through lines 23--23, respectively, of the checkvalve housing 440 having an air opening 512, an externally threadedconnecting tube 514, a check valve housing chamber wall 516, an O-ringannular groove 518, a shoulder 520 and an externally threadedcylindrical outlet connection portion 522. The check valve housing 440is intended to receive the check valve 444 (FIG. 10) within the checkvalve housing chamber wall 516 to be threaded into the valve seat outlet454 (FIG. 10) to receive air from the chamber when the valve assembly352 is open and to be connected by the externally threaded outletconnection 522 to the tank outlet housing 446. The O-ring groove 518receives the O-ring 442 to provide a sealing connection between thechamber wall and the check valve 444.

In FIGS. 24 and 25, there is shown an elevational view and a sectionalview taken through lines 25--25 of FIG. 24 of the check valve 444respectively, having an inlet opening 524, outlet openings 546A-546C, anouter housing 526, an inner housing 532 and a spring-loaded valveassembly within the inner housing 532. The outer wall 536 includes aninwardly extending annular flange 539 having an edge 530 abutting thespring-loaded valve. The inner housing includes annular insulation 542that forms when a seal is between the outer and inner housings and, whenthe valve is closed, a seal is between the spring-loaded valve and theinner housing.

The spring-loaded valve includes a helical compression spring 534, ashaft 538, an air blocking face 540 and an air opening 544. The shaft538 fits within a shaft opening 536 aligned in the inner and outerhousings and the outlets 546A-546C pass through both the inner and outerhousing.

With this arrangement, air pressure from the outlet 454 (FIG. 10) causescommunication between the compartment 422 and the opening 524 to exertpressure against the air blocking portion 540 except for a slightequalizing trickle of pressure through the opening 544. When the purgevalve 352 (FIG. 10) is opened, the increased pressure forces the shaft538 further through the opening 536 against the pressure of the spring534 to permit air to escape aroung the face 540 after it clears thesealing material 542 and permits it to pass through the openings546A-546C. Thus an onrush of air passes through the ring of openings546A-546C into the bubbler through the outlet 446 into the bubbler 132.

In FIGS. 26 and 27, there is shown a right elevational view and atransverse sectional view of the tank outlet housing 446 havinginternally-threaded connection walls 550, inwardly sloping outer walls552, a connecting wall for the purge air line 382 (FIG. 10) that leadsto the bubbler 132 and an outlet 558 for the purge air line 382. Theconnecting walls 550 are threaded on the externally-threaded walls 522of the checkvalve housing so that air from the check valve flows inthrough the sloping walls 522 through the outlet 556 into the airpressure sensing outlet 384 (FIG. 10) and through the outlet 558 to thepurge air line 382 which leads to the bubbler 132. Some air flowsthrough the outlet 556 into the air sensing port 384 (FIG. 10) toprovide pressure information.

The air hole 544 may provide a path to air that reduces the pressurebetween the purge valve assembly 352 in embodiments to be used at deeplocations to equalize the pressure at the outlet and lower portion ofthe purge valve. This path is completed through a connection 383 (FIG.5) from the sensing outlet 556 to lines 383 and 251. This pressure maybe at either the bubbler in some embodiments or atmosphere in otherembodiments so as to maintain a pressure differential referenced to afixed standard to control the opening of the purge valve assembly 352.

In operation, air is supplied to purge tank 350 from reservoir 312 (FIG.5) or by pump 402 (FIG. 5) in remote section 14 (FIG. 1) through airline 398 (FIG. 5). The air enters the accumulator assembly 356 of purgetank 350 through inlet 410. The air in accumulator assembly 356 remainsat the same pressure as the air in the reservoir 312 as long as O-ring424 is seated against valve seat 358 which is part of valve seat plate354. The spring 370 provides the force on purge valve assembly 352 toseal O-ring 424 against valve seat 358 thus stopping air from flowingout of accumulator assembly 356. The rolling diaphragm 364 is retainedbetween valve seat plate 354 and tank bottom plate 372 with screws 374Aand 374G and washers 376A and 376B.

The accumulator assembly 356 supplies air through holes 430A and 430B(FIG. 13) to inner portion 432 (see FIG. 10) of purge valve assembly352. The inner portion 432 of purge valve assembly 352 is defined by thelocation of O-ring 424 against valve seat 358. The outer portion 434 ofthe purge valve is considered to be that area of the purge valveassembly 352 external to the circular location of O-ring 424 againstvalve seat 358 inclusive of the area of the rolling diaphragm 364 whichwill also apply force to the valve when air pressure is encountered.

Air does not flow out of the accumulator assembly 356 through holes 430Aand 430B unless the air pressure in accumulator assembly 356 times thecross sectional area of the inner portion 432 of valve is equal orgreater than the force of spring 370. When the air pressure issufficient to overcome spring 370, air will proceed to flow into valvechamber 436. Since the air cannot flow by valve assembly 352 which hasrolling diaphragm 364 sandwiched between the valve seat plate 354 andtank bottom plate 372, the air can only proceed through valve chamber436 to the purge tank outlet assembly 378. The hole 458 in tank bottomplate 372 vents the backside of rolling diaphragm 364 to atmosphere inthe preferred embodiment and to the bubbler pressure in otherembodiments to provide a reference pressure for the actuation of thepurge valve switch. provide a reference pressure

The purge tank outlet assembly 378 includes check valve housing 440,O-ring 442, check valve 444, and tank outlet 446. Check valve 444 isinstalled into check valve housing 440 with O-ring 442 to eliminateunwanted air leakage. Check valve 444 has a small hole 544 (FIG. 25)drilled in it to provide a slow controlled leak.

To perform a purge cycle, the accumulator assembly 356 is maintained atessentially the same air pressure as an air reservoir 312 in remotestation 14 or 14A (FIGS. 1 and 5). The remote station turns on its airpump thus increasing the air pressure in its reservoir 312 and inaccumulator assembly 356. Air pressure builds in accumulator assembly356 until pressure on inner portion 432 of purge valve assembly 352starts to overcome the force from spring 370. As the valve element thepurge valve assembly starts to open, air flows through holes 430A and430B in valve seat plate 354 through the interface between O-ring 424and valve seat 358 and then into valve chamber 436. Some air flowsthrough hole 544 in check valve 444 but less than that is flowing by theinterface between O-ring 424 and valve seat 358.

Because the pressure begins to rise in valve chamber 436 from the airflowing past the O-ring, the force due to air pressure on inner portion432 times its cross sectional area plus the air pressure on the outerportion 434 times its cross sectional area is sufficient to fully openpurge valve assembly 352. Once the purge valve assembly 352 is open, airflows rapidly through holes 430A and 430B in valve seat plate 354 intovalve chamber 436. The increased pressure in chamber 436 causes checkvalve 444 to quickly open thus completing the air path that allows airto rush through holes 430A and 430B into chamber 436 through check valve444, down through bubbler tube 132 and out bubbler outlet 134 (FIG. 2).This rush of air sweeps away particles or growth in the bubbler tube andits outlet.

As air rushes out bubbler tube 132, pressure drops in accumulatorassembly 356 and in valve chamber 436. When the air pressure hasdecreased so that air pressure in valve chamber 436 times crosssectional area of outer portion 434 plus air pressure in accumulatorassembly 356 times the inner portion 432 approaches spring force, thevalve starts to close. The purge valve assembly 352 fully closes as airpressure continues to drop. Pressure in the valve chamber 436 continuesto drop after the purge valve assembly 352 has closed since check valve444 closes at a lower pressure. Pressure in valve chamber 436 continuesto drop rapidly until check valve 444 closes, at which time the airpressure drops more slowly as air flows out hole 544 in check valve 444.

If air is no longer flowing from reservoir 312 to accumulator assembly356, the pressure in valve chamber 436 drops to that in bubbler tube132. If air is still flowing into accumulator assembly 356, purge valveassembly 352 may cycle again before pressure in valve chamber 436 dropsto that pressure in bubbler 132. Since there may be some residualpressure on the outer portion 434 of purge valve assembly 352, the valvemay open at a somewhat lower pressure. If the controller 312 continuesto supply air, purge tank 386 continues to cycle, providing quick burstsof air whenever the air pressure in accumulator assembly 356 buildssufficiently to trip purge valve assembly 352.

The components may be sized for the desired results. In the preferredembodiment, the desired pressure in accumulator assembly 356 to openpurge valve assembly 352 is between 51/2 psi and 81/2 psi. This rangepermits the controller to perform other functions using the same airreservoir without triggering a purge operation. However in otherembodiments, the range may be narrower and the values may be selectedtogether with the size of the inner and outer areas of the valve elementand the resistance of the spring in accordance with the depth that is tobe used.

This is accomplished by selecting an O-ring and O-ring groove thatresults in an effective pressure diameter of about 0.83 inches. Theeffective cross-section for inner portion 432 is about 0.55 SI (squareinches). A spring with a spring rate of about 15 lb/in that iscompressed about 0.28 inches in the closed position is selected. Thisselection allows the purge tank to typically dump air at pressuresbetween 7 and 8 PSI. These components could be easily changed to achievedifferent flow pressures.

The cross sectional area of outer portion 434 of purge valve assembly352 is about 1.3 SI based on the effective cross sectional pressure areaof rolling diaphragm 364 less inner portion 432. The total of innerportion 432 and outer portion 434 is about 1.84 SI. The purge valveshould thus close at about 21/4 PSI. The ratio between opening andclosing is about 3 to 1. This ratio can be varied according to thedesired effect.

The down stream check valve 444 has a 1/2 PSI to a 1 PSI crack pressure.At slightly higher pressures, the valve allows air to flow quite freely.By restricting flow until pressures of at least 1/2 PSI builds up invalve chamber 436, the total force on the purge valve assembly 352 issufficient to allow the purge valve to fully open. It is important thatthe pressure to open and to close valve 444 is less than it takes toclose purge valve 352. If not, check valve 444 closes before purge valveassembly 352. This traps air pressure on outer portion 434 which alongwith pressure on inner portion 432 keeps purge valve assembly 352 open.Check valve 444 then appears more like a regulator with a more constantflow of air instead of bursts.

The hole 544 in the check valve 444 is 0.012 diameter. This is sizedsmall enough to restrict the flow of air out hole 544 to less than thatflowing in tank inlet 410 taking line losses in air line 398 and pumpingcapacity in controller 10 into consideration. Hole 544 may be downsizedto as small or even smaller than 0.008 if line 398 reaches lengths inexcess of several hundred feet. However, if hole 544 becomes too small,the pressure in valve chamber 436 will not drop quickly. The additionalpressure on the outer portion 434 will cause the purge valve assembly352 to open at a lower pressure.

The hole 544 in the check valve 444 communicates pressure at the bubbleroutlet into valve chamber 436. If the bubbler outlet 134 (FIG. 3) issensing high heads of pressure, this pressure has a pressure effect onouter portion 434 because of the air leakage through the hole 544 in thecheck valve. Thus, the spring 370 must apply more force at deeperdepths. In a system that encounters a wide range of pressures at thebubbler outlet, the outer portion should have a cross section less thanthe inner portion so that it is less sensitive to the pressurevariations.

The pressure in the accumulator or equivalent structure in embodimentsof the valve used in some other applications such as for controllingbladder pump inflation and deflation, may have pressures of between 5 to300 psi. In purge valves for bubblers, the pressure in the accumulator422 may be between 1 and 30 psi. The force exerted by the spring 470 insuch applications must also be in range of the force of the pressuremultiplied by the area for triggering the valve. The accumulator and theconduits should provide a flow rate to the bubbler port that is at leastone cubic inch per second. Preferably, the flow from the accumulatorthrough the flow line should be in the range of velocity of between 6cubic inches per second and 30 cubic inches per second. The actuallyrequired flow rate will depend on the size of the bubbler conduit andport.

In operation, the remote station 14 and the flow-stream local station 12are brought to a site, such as a manhole or the like. The air andelectrical conduits are connected, the bladder 80 (FIG. 2) is deflatedand the flow housing 60 (FIG. 2) is inserted into the pipe 46 (FIG. 2).The bladder is then inflated to grip the inside of the pipe 46 (FIG. 2)and the adjustable mounting unit 44 (FIG. 2 and FIGS. 5-8) is thenadjusted or leveled.

To level the local station along its right to left axis, the clampingplates 140 and 142 are pivoted so that they hold the gate housing 74horizontally with the end of the pipe housing abutting the outer platesor being adjacent thereto but leaving sufficient room for theiradjustment. Leveling is accomplished by turning the bolt 240 (FIG. 8) orits counterpart on the opposite side while holding the unit so that thebubble is aligned along its right to left centerline. The wing nuts 234are then tightened.

To level the local station along its front to back axis, screws150A-150D (FIG. 3) are loosened and the housing lifted until the bubblelevel 156 (FIG. 3) indicates that the flow path is level. The screws150A-150D are then tightened. The bladder 80 may be further inflated bypumping air through the tube 82 (FIG. 2) to seal against the flow andthe leveling process repeated. It is desirable to check the bubblerlevel 156 and readjust the flow bed if it is now off-center.

The bubbler may be periodically corrected for drift by incorporating anelectrically-controlled valve in the line to: (1) close the line towater; (2) open the portion of the line communicating with the highpressure side of the pressure-to-electrical transducer to atmospherewhile the low pressure side is at atmospheric pressure to develop a zerosignal for calibration; and (3) to connect the high pressure side of thetransducer to atmosphere through the valve 316. A check valve may beused to prevent the air from flowing from the bladder 80 back to thereservoir (FIG. 10) and prevent the inflow of water as it depressurizes.

In the preferred embodiment, a look-up table has been constructed whichcorrelates gate position and depth upstream of the gate (head ofpressure) with the flow rate. This table has been constructed byadjusting the gate and making measurements using a weigh tank and timerto arrive at values corresponding to different positions of the gate anddifferent depths of head. This look-up table is used by the controllerto provide data concerning the flow rate in response to received signalsfrom the gate sensing system 20 and depth sensing system 24. Thesecoordinates are used in a well known manner to access data in thelook-up table and provide a flow rate. Other look-up tables with greateraccuracy or less accuracy or for modifications of the equipment can beconstructed in a similar manner.

Once the look-up table is in place, the equipment can be operated in anumber of modes to obtain flow measurement and to provide a simulatedstilling well for drawing samples. In its operation, some benefits areobtained by maintaining a clean, flushed flow path and this can beconveniently automatically accomplished, if desired. For this purpose,the gate assembly 62 is periodically closed, a head of liquid createdand then opened. The onrush of fluid clears the flow bed for the benefitof a bubbler port 24 (FIGS. 1-4) or for the sample port at 26.

The flow meter may operate in any of several modes, for example, thegate may be moved to maintain a predetermined constant head and thelook-up table may utilize gate position at the predetermined head todetermine flow rate. To accommodate many different flow rates, severalsuch positions can be selected, each of which has a look-up table.

In an alternative mode of measurement, the gate may select incrementalpositions such as fully open in which equations for fully openedconduits can be used, or it can assume incremental positions appropriatefor the flow rate to maintain a head within the dynamic range of themeasuring instruments and a look-up table can be used for that positionand different depths, or for example, the gate may be changed inposition and the rate of change of head and increase in head may becorrelated with flow rate.

Another method of flushing and then measuring flows using a look uptable is to fully close the gate to reduce flow to near zero. Theupstream conduit will begin to fill, thus increasing the head. At apredetermined first head, the gate opens and flushes the line atvelocities that can support a large amount of solids. As the conduit isflushed, the head drops. At a second predetermined head, the gate againcloses to reduce flow to zero and refill the conduit. Such a methodconsumes more power in positioning the gate, but is more effective inespecially low flow conduits that have excessive solids.

In this method of flow monitoring, the gate may be fully closed oralmost closed while filling the conduit. When flushing and lowering thehead, the ideal gate position is slightly into the flow stream althoughit may be also lifted out of the flow stream. The measurements of gateposition and depth are at sufficiently frequent intervals and the lookup table sufficiently detailed so that the readings during the closedgate and open gate positions can be plotted and measurements of flowrate that are not distorted by such fluctuation used or the time periodof averaging can be selected to be large enough to average out the zeroflow to high flow fluctuations.

The different modes of operation are each possible because, closing thegate assembly 62 relative to the flow path, causes the flow to "back-up"and the level of the liquid behind the multiple position gate assembly62 to increase at a rate related to rate of flow of the fluid.Similarly, the raising of the gate opens the flow path and reduces itscross sectional blocking area, increasing the cross section of flow,causing the level of fluid to decrease at a flow rate related to therate of flow of liquid in the pipe. Similarly, if the gate is moved to afixed position and maintained in that position, the head stabilizes at alevel related to the flow of fluid in the pipe 46. All of these factorsmay be utilized in determining the flow rate.

To move the multiple position gate assembly 62 in a direction whichreduces the flow cross section, air is pumped into the chamber above thepiston 106 causing it to move downwardly and stabilize at a locationwhere the spring 108 and forces of upstream liquid counteract thepressure. Similarly, when the gate assembly 62 is to be opened, air isremoved causing the spring 108 to move the piston 106 upwardly and thusmoves the rod 102 upwardly. Any movement is sensed by the LVDT and themovement and new location are transmitted to the remote unit which maybe used for correction of the location of the gate in some modes and/ordirectly calculate flow rate in other modes.

There are several modes available for cooperation between the samplerand the electronics and air portions of the controller at the remotestation. For example, sampling may be performed periodically in units oftime. As the units pass, the gate assembly 62 may be closed to back upthe liquid so that the depth at which sampling occurs is increasedsufficiently for a sample which is above the inlet port for the entiretime of sampling and the sample is thus more representative. A flushcycle may be performed before sampling, if desirable. In another moderelated to flow, flow rate may be determined and timed and when apredetermined amount of volume of liquid has passed, the gate may closeto raise the volume to a sufficient height for an accurate sample.

In a sequence using the purge system, the step 476 reads the gateposition and is followed by a read liquid level step 478 which isfollowed by a control gate step 480 and a calculate flow step 482. Thecalculate flow step 482 is followed by a decision 484 to determine iftwo seconds have elapsed. If they have, the step to increment the flowtotalizer is performed at 486; otherwise, the step of forming theplotter image is performed at 488.

After forming the plotter image, a decision is made as to the prioritysequence two at decision step 490. If it is a priority sequence twoinvolving the bubbler, a gate flush is performed at step 492. If it isnot, then the time is checked again at step 485. If it has not, theprogram returns to the timing step and repeats it.

If the time has elapsed, the program checks on the last clearing step atstep 487. If the last clearing step was a purge step shown 489, than theclearing step is performed at the super bubble step 494 by increasingthe pressure through the bubbler. If the last clearing step was not apurge step, than the purge step is performed. After clearing thebubbler, the program proceeds to another sequence not involving thepurging of the bubbler and described in the aforementioned patentapplication to Carson et al.

Because the valve is able to automatically release fluid and accumulatefluid at periods of time related to the pressure setting of the biasingmember and the pumping rate of fluid into the accumulator, it has beenproposed that the valve may be used for other purposes such as tocontrol the cycling of a bladder pump of the type that repetitivelyinflates and deflates a bladder to change the volume of a pumpingchamber and thus pump fluid.

From the above summary, it can be understood that the novel method andapparatus of this invention has several advantages, such as for example:(1) it is relatively simple, inexpensive and easy to use; (2) it permitsrelatively precise depth measurements, even in flow streams carryingmaterial capable of blocking a bubbler outlet port; (3) it is capable ofcooperating with a versatile apparatus that can be used both to measureflow rates and take samples in a wide variety of streams and at a widevariety of different depths of flow and flow rates; (4) it is capable ofgreat precision under difficult measuring conditions; (5) the apparatuscan be used to perform a number of different measuring methods; (6) thevalve can be used without electrical connection at the valve itself; and(7) it permits high-volumetric-rate air purging operations using asource near the bubbler outlet port without electrical connection.

Although a preferred embodiment has been described with someparticularity, many modifications in variations are possible in thepreferred embodiment without deviating from the invention. Therefore, itis to be understood that, within the scope of the appended claims, theinvention may be practiced other than as specifically described.

What is claimed is:
 1. Apparatus for maintaining constant back pressurein a flow line of a bubbler comprising:an accumulator; means for pumpingair into the accumulator; a release valve for the air; means for openingthe release valve in the accumulator when a predetermined pressure isreached; means for rapidly allowing a burst of the air at a substantialpressure and velocity to flow from the accumulator through the flow linewhen the release valve is opened; and means for closing the releasevalve when the pressure drops below a predetermined value wherein therelease valve is repeatedly opened to maintain the bubbler lineunclogged.
 2. Apparatus according to claim 1 in which the means foropening a release valve in the accumulator when a predetermined pressureis reached comprises:a biasing means; a release valve element having asmall portion and an additional portion; and means for accumulating airin the accumulator until the pressure in the accumulator against theeffective area of the small portion of a release valve element overcomesthe resisting force of the biasing means, wherein the valve elementmoves slightly, permitting air to flow over a larger area of theadditional portion of the valve element, wherein the increased effectivepressure area of the valve increases the force rapidly to cause thevalve to snap open.
 3. Apparatus in accordance with claim 1 in which themeans for opening the release valve includes means for opening therelease valve when the predetermined pressure is in a range of between 5and 300 pounds per square inch.
 4. Apparatus in accordance with claim 1in which the means for rapidly allowing a burst of air to flow from theaccumulator through the line includes means for allowing a burst of airto flow at a velocity of between 6 cubic inches per second and 30 cubicinches per second.
 5. Apparatus in accordance with claim 1 in which thebubbler includes means for measuring the depth of a fluid from the backpressure in said flow line.